Lighting unit

Abstract

A lighting unit is provided with a cutoff line forming member disposed between a projection lens and a first light source and having a tip edge positioned in a vicinity of a rear focal point of the projection lens. The cutoff line forming member is capable of shielding a part of a light reflected by a reflector, thereby forming a cutoff line of a light distribution pattern for a low beam. An additional reflector is capable of collecting a light emitted from a second light source in a vicinity of the rear focal point of the projection lens. The light emitted from the second light source is collected in the vicinity of the rear focal point of the projection lens in a state in which the tip edge of the cutoff line forming member and the rear focal point of the projection lens are relatively separated from each other, and a light distribution pattern for a high beam is thus formed.

What is claimed is: 
     
       1. A lighting unit for a vehicle comprising:
 a projection lens disposed on an optical axis extended in a longitudinal direction of the vehicle; 
 a first light source disposed behind a rear focal point of the projection lens; 
 a second light source; 
 a reflector configured to forward reflect a direct light emitted from the first light source close to the optical axis; 
 a cutoff line forming member disposed between the projection lens and the first light source; and 
 a light collecting portion configured to collect a light emitted from the second light source in a vicinity of the rear focal point of the projection lens, 
 wherein a relative position of a tip edge of the cutoff line forming member and the rear focal point is changeable between a first position and a second position, 
 wherein the tip edge is positioned in a vicinity of the rear focal point in the first position, and the tip edge of the cutoff line forming member is apart from the rear focal point in the second position, 
 wherein, in the first position, the cutoff line forming member shields a part of a light reflected by the reflector which passes through a lower part of the rear focal point to form a cutoff line of a light distribution pattern for a low beam, and 
 wherein, in the second position, the light emitted from the second light source is collected in the vicinity of the rear focal point to form a light distribution pattern for a high beam. 
 
     
     
       2. The lighting unit according to  claim 1 , further comprising a reflecting surface provided on an upper surface of the cutoff line forming member, wherein the reflecting surface of the cutoff line forming member reflects the light emitted from the second light source toward the projection lens in the second position. 
     
     
       3. The lighting unit according to  claim 2 , wherein the reflecting surface of the cutoff line forming member is formed by a plane, and
 wherein the light collecting portion comprises a reflecting surface formed in a substantially elliptical sphere shape having focal points on a point in a symmetrical position with the rear focal point with respect to the plane of the reflecting surface of the cutoff line forming member in the second position and on the second light source. 
 
     
     
       4. The lighting unit according to  claim 2 , wherein the reflecting surface of the cutoff forming member comprises a first plane and a second plane,
 wherein a step extending in the longitudinal direction of the vehicle is formed between the first plane and the second plane, and the cutoff line is formed by the step, 
 wherein the light collecting portion comprises a first reflecting surface and a second reflecting surface, 
 wherein the first reflecting surface is formed in a substantially elliptical sphere shape having focal points on a point in a symmetrical position with the rear focal point with respect to the first plane in the second position and on the second light source, and 
 wherein the second reflecting surface is formed in a substantially elliptical sphere shape having focal points on a point in a symmetrical position with the rear focal point with respect to the second plane in the second position and on the second light source. 
 
     
     
       5. The lighting unit according to  claim 2 , wherein the reflecting surface of the cutoff line forming member is formed in a substantially elliptical sphere shape having focal points on the rear focal point and on the second light source. 
     
     
       6. The lighting unit according to  claim 1 , wherein the light collecting portion comprises a reflecting surface formed in a substantially elliptical sphere shape having focal points on the rear focal point of the projection lens in the second position and on the second light source. 
     
     
       7. The lighting unit according to  claim 1 , wherein the tip edge of the cutoff line forming member is capable of moving to a position placed apart from the projection lens along the optical axis.